Electric switch gear



April 1, 1931.

A. ALLAN ET AL ELECTRIC SWITCH GEAR 2 Sheets-Sheet 1 Filed April 28, 1928 April A. ALLAN ET AL 1,800,042

ELECTRIC SWITCH GEAR Filed April 2a, 1928 2 Sheets-Sheet 2 I plunger rod passes.

' gland are shaped openings in the casing com- Patented Apr. 7,

UNITED STATES. PATENT OFFICE ARCHEALD ALLAN, OF TYNEMOUTH, AND JAMES MIRREY, OF EAST BOLDON, ENG- LAND, ASSIGNORS TO A.

REYROLLE & COMPANY LIMITED, OF HEBBURN-ON-TYNE,

ENGLAND, A COMPANY OF GREAT BRITAIN ELEUI'BIC SWITCH GEAR Application filed April 28, 1928, Serial-No. 278,758, and in. Great Britain June 11, 1827;

This invention relates to electric switchgear and particularly to that type of gear which is operated by air or other fluid under pressure.

5 In switchgear according to the present invention the switch-operating rod or plunger is, o erated directly by pneumatic or other fluid pressure ap lied directly to a cylinder or iston mounted on the rod.

,7 onveniently a cylinder is attached to the rod' or-plungerto form an extension thereof. This cylinder cooperates with a fixed head .or piston and compressed air is admitted through a central tube into the cylinder through a hole in the tube just above the y fixed head to move the cylinder and the rod and close the switch. 3

I This central air inlet tube carries the fixed v lston or head at its lower end and thus may regarded as a stationary piston rod. It vis fixed at its upper end by passing through a cap into a chamber at the upperendof a casing which "encloses the movable cylinder. This chamber is in direct communication with the compressed air supply. The upward movement of the cylinder is/arranged to cause rotation of a notched disc or cam cooperating with hold the switch in its closed position until released y an electromagnetic trip or like mechanism. When released the switch is opened or its opening movement accelerated by a kick-off spring which is conveniently arranged to act on the upper end of the cylinder. Preferably theoutside of the cylinder is 'formed as or provided with a rack engaging with a toothed pinion on a shaft which carries the notched disc or cam.

' The cylinder with" its rack is enclosed in a cover and 1n the lower (part of such casing is fixed a head or glan Somewhat above this municating with the'oilin the tank and thus, on the opening movement of the switch, i. e. the downward movement of'the plunger rod and cylinder, the oil passes freely out of the casing through the openings. 'Towardsthe end of this movement the cylinder closes these a catch oi detent to casing projecting above and below the tankthrough which the openin s and the oil can no longer pass freel throng them but has to find its way throng the various clearance spaces. Thus a dashpot or retarding effect is also provided at the end of the opening movement.

This improved construction of neumatic operating gear is very suitable or use in multi-phase switchgear, and in one construc-v tion of three-phase gear the chambers at the top of the casings are all in connection with a common pipe through which the supply ofsupply is cut off immediately the trip coil is energized, and such compressed air as has been admitted is allowed to escape'so that the switch immediately opens.

This construction affords the protection that is provided by the free handle feature generally embodied in switch-operating mechamsms.

The shafts carrying the pinions which engage with the cylinder racks are coupled together preferably by couplings which alldw for small "differences in alignment, and one mechanism is provided for holding and tripping all three switches. This mechanism conveniently comprises a notched disc or cam cooperating with a detent lever controlled through a toggle by a trip electromagnet.

This arrangement is provides forthe simultaneous direct pneumatic operation of all three phase switches of the gear. I

In the accompanying drawings,

Figure 1 is a central vertical section through a portion of oneconstruction of switchgear according to thisinvention,

Figure 2 shows diagrammatically the esextremely simple and sential parts of a preferred pneumatic and electromagnetic control mechanism, and

K Figure 3 is a diagrammatic perspective view of one embodiment of the invention as applied to three-phase switchgear.

In these drawings, A represents the plunger rod of a switch carrying a cross bar A which, when the switch is closed, completes the circuit between two fixed brushes or other contacts B (Figure 2). Surrounding this plunger rod A is a casing C (Figure 1.) secured to a hood D which may be part of the cover of a tank containing oil in which the switch operates.

At the top of the casing C is a fixed head or chamber E to which is secured a central tube E having at its lower end a fixed head or piston E With this fixed piston E 00- ]operates a cylinder F provided with a head F sliding on the fixed tube or piston rod E .The lower end of this cylinder F is. secured to the plunger rod A and a rack F on one side of the cylinder engages with a toothed-pinion G mounted on a shaft G. In all the figures the switch is shown in its closed position, i. c. with the plunger rod A raised. This up-. ward or closing motion is brought about by fluid under pressure, hereinafter referred to as compressed air, admitted from a, pipe H into the chamber E whence it passes down through the tube E and out at an opening E into the space between the head F ofthe cylinder F and the fixed piston E It will be seen by reference to Figure 1 that there are two small tubes within the central tube E each of these terminating in a capped outlet at the top. One of these small tubes J ends just above a space E in the fixed piston E and it is provided to allow any moisture which may accumulate in that space to be blown off. The lower end of theother small tube J passes through the piston E and is intended to prevent back pressure between the lower face of the fixed piston E and the lower closed end of the cylinder F as the latter rises. It also allows the cylinder to fall freely on the opening movement.

If-desired any suitable form of valve may be provided to cooperate with this tube J to close it just before the closing (upward) movement of the cylinder is completed and thus introduce a dashpot effect at theend of the closing stroke. Or alternatively, the lower end ofthe cylinder may be shaped to cooperate with a correspondingly formed projecting part of the piston with the same object. Neither of these devices is essential and they are notshown in-the drawings.

The opening downward) movement of the cylinder and plunger rod may be mainlv due to gravity, but a kick-offspring K is provided to accelerate the initial portion of the opening movement. The lowerend of the casing C is provided with a' gland C through which the plunger rod A passes, and at some ward movement of the cylinder, expelled through the opening G into the surrounding tank. 'The area of the opening is gradually diminished by the descending lower end of the cylinder and the opening finally closed so that any remaining oil has tofind its way out into the tank through various small clearance spaces. This introduces a dashpot effect at the end of the opening stroke.

The general operation will now be described with reference to the diagram forming Figure 2. The pipe H is connected to a port L which can be placed in communication either with a source of compressed air at L when an inlet valve L is opened (as shown) against the action of its spring L or with the atmosphere through the port L when the inlet valve L is closed and an outlet valve L opened. These two valves are on a spindle L provided with a piston L in a cylinder containing the outlet port L and an inlet L This inlet L communicates with a port M in a relay air valve chamber M provided with a spring-controlled air inlet valve M and an outlet valve M These two valves M and M are on a spindle M which can be raised against the action of a'spring M by an electromagnet M in a circuit shown as controlled by a switch M There is a gap at N in the circuit of the electromagnet M closed by the armature of a trip electromagnet N when that magnet is deenergized but opened when the trip circuit is closed.

On the shaft G carrying the pinion G1 is mounted a notched or cam disc 0. For the sake of clearness in the diagram forming Figure 2 this is shown separately, but the two shafts are each lettered G and the chain line connection indicates that they rotatetogeth- I A pivoted detent lever P has a roller P er. which engages with the notch in the disc 0, as shown in full lines in Figure 2, when the shaft G has been rotated by the raising of the controlled by a lever P In Figure 2 the toggle is shown in full lines inthe set position and in chain lines in the position which it takes up when the toggle is broken by the lever P being operated by the trip electroma et N or. by a hand tri N It will be un erstood that as soonas t e toggle is broken the detent lever P can rise under the action of the disc 0 which is rotated by the rotation of the shaft G due to theopening (downward) movementof the cylinder F and plung- I er rod A.

In Figure 2-it is assumed that the trip electromagnet N is deenergized and that thecircuit of the electromagnet M has just-been pressed air from L throu t electromagnet M by closed by the switch M". This has opened the relay a1rvalve inlet M and allowed comressed air to pass from L through the chamr M and port M to the inlet piston L has moved to the left, thus opening the main inlet valve. Land admitting comh the port L to the pipe H Consequently e switch has been closed, the detent lever P has fallen under the action of gravity or a spring (not shown) and has engaged the notch in the disc 0 and the toggle P has assumed its set position.

If it be assumed that the closing of the switch M controlling the relay air inlet valve is only for a short period of time, which is normally the case, then as soon as the switch is opened air inlet valve M and open the outlet valve M L is then placed in communication with the atmosphere through the port M and the valve spindle L will move to the right under the action of its spring L This cuts off the compressed air supply L from the port L and pipe H and by the opening of the valte L places that port and pipe in communication with the atmosphere through-the port L Thus, although the switch is closed and retained closed by the detent lever P and f its toggle, it is ready to open instantly when the toggle is broken by the trip. It should be noted that the control of the circuit of the the trip electromagnet N provides a very efficient free handle action, for even if the valve spindle M is in the act of being raised by its electromagnet M", and conditions arise which energize the trip electromagnet N the electromagnet M is immediately' deenergized and the movementsof the air inlet valves necessary for the closing of the switch cannot be completed.

Figure 3 is intended to show the application of the invention to three-phase switchgear. The righthand switch is shown in elevation enclosed in its casings, the intermediate switch has its casings removed, the cylinder F being shown in in section. It will be seen that there is one air supply pipe H for all three switches controlled by a valve L which would be constructed so as to operate as described in detail with reference to Figure 2. p The shaft G is in a number of lengths joined by couplings G which allow for slight differences in alignment, and one notched disc 0 with-its detent and trip mechanism suflices for all three switches.

What we-clai'm as our invention and desire to secure by Letters Patent is 1. In electric switchgear the combination of a switch-operating rod, :1 cylinder forming an extension of such'rod, an mlet tube within'said cylinder, a head on said tube constituting a piston for the cyllnder, an opening in said tube permanently connecti ng cylport L. The

the spring M will close the relay elevation, and in the I opening said leftha'nd switch the cylinder is shown partly said inlet tube flow of fluid from said source to said opening in said inlet tube to-move said cylinder and switch-operating rod.

2. In electric switchgear the combination of a switch-operating rod, a cylinder forming an extension of such rod, an inlet tube within said cylinder, a headon said tube constituting a piston for the cylinder, an opening in said tube permanently connecting cylinder space above said head to said tube, a source of fluid under pressure, a supply pipe from said source to said inlet tube, an electromagnetically-operated valve controlling the flow of fluid from said source to said supply pipe, means in said valve for opening said supply pipe to the atmosphere.

3. Inelectric switchgear the combination ofa switch-operating rod, a cylinder forming an extension of such rod, an inlet tube within said cylinder, a head on said tube constituting a piston for the cylinder, an opening in said tube permanently connecting cylinder space above said head to said tube, a source of fluid under pressure, a' supply pipe rom said source to said inlet tube, an electromagnetically-operated valve controlling the flow of fluid from said source to said suppl to move the cylinder and switch in' one d1- rection to close the switch, means in said valve for connectingsaid supply pipe to atmosphere and meaiis operative when said supply pipe is connected to atmosphere for moving said cylinder and switch-operating rod in the other direction to open the switch.

4. In electric switchgear the combination of a switch-operating rod, a cylinder forming an extension of such rod, an inlet tube within said cylinder, a head on said tube, a source of fluid under pressure, a supply pipe from said source to said inlet tube, a valve con-' trolling the. flow of fluid from said-source to said supply pipe, means in said valve for supply pipe to the atmos here, an electromagnet controlling said va ve, a

circuit including said electromagnet and havv inga gap therein, a detent for holding said switch-operating rod when the switch is closed, trip mechanism for releasing said detent, an electromagnet for operatin said trip mechanism, said electromagnet w ergized closing the gap in the circuit containing the valve-operating electromagnet and 4 opening said gap when energized.

5. In electric switchgear the combination of a switch-operating rod, a cylinder forming an. extension of such rod, an inlet tube within said cylinder, a head oh said tube, means for admitting fluid under. ressure to to move said cy inder and switch-operating rod, a rack on said c linder, a shaft bearing a pinion engaging with said rack, a'detent engaging with sald shaft to en deenretain said linder and switch-operating rod in;the closed position of the switch, and trip mechanism for releasing said detent.

6. In electric switchgear the combination I of a switch-operating rod, a cylinder forming an extension of such rod, an inlet tube Within said cylinder, a head on said tube, means for admitting fluid under pressure to said inlet tube to move said cylinder and switch-operating rod, a rack on said cylinder, a shaft bearing a pinion engagingwith said rack, a detent engaging with said shaft to retain said cylinder and switch-operating rod in the closed position of the switch,'toggle mechanism for controlling said detent, trip mechanism for breaking said toggle, and an electromagnet for operating said trip mechanism. 7. In electric switchgear the combination I of a switch operating rod, a cylinder forming an extension of such rod, an inlet tube withinv said cylinder, a head on said tube constituting a piston for the cylinder,- an opening in said tube permanently connecting cylinder space above said head to said tube,

meansin said tube through which accumulated moisture is expelled, a source of fluid under pressure and an electromagnetically operated valve controlling the flow of fluid '30 from said source to said opening in' said inlet tube to move saidcylinder and switchoperating rod. I r

In testimony whereof, we have signed our names to this specification. ARCHIBALD ALLAN.

JAMES MIRREY. 

